Commode (toilet) flush valves are customarily installed in the bottom of toilet tanks. When opened they permit the outflow of stored water to the commode, and when the tank is emptied they close so as to enable water to be stored for the next flush cycle. During the time the water in the tank is below some storage level, a tank valve is open so as to refill the tank. Of course it also adds the outflow water while the flush valve remains open.
The tank valve is sensitive to the level of the water in the tank. It is open when the water is below some selected storage level, and hopefully will be closed when the water is at or above that level. Customarily some float-type device is responsive to the water level, and opens or closes the tank valve.
The problems of water availability and of sewage water disposal have become very severe, and municipalities are requiring that newly-installed flush toilets operate on very small volumes of water per flush. Even without these constraints, there are substantial incentives to use short flush cycles in existing toilets because of increasing cost of water, and in many areas of decreasing allotments of water per meter served.
Many solutions have been proposed to decrease the volume of water discharged per cycle. Perhaps the most familiar is a brick or partition placed in the tank to reduce the stored volume. This will reduce the volume discharged per cycle without changing the levels in the tank at which the tank valve opens and closes. As a corollary, this means that the exit pressure of the water, each flush, goes from maximum at the start to minimum at the finish. Also this means that the rate of flow diminishes, which is not helpful to a good flush.
This is a time-honored "fix", but one ought to do better. For example, a faster flow rate could be available if flow only occurred between two upper elevations, well above the exit port.
Such a solution is not possible with conventional flush valves because of their configuration. The conventional flush valve is a downwardly-open cup which, when the valve is closed opens directly into the outlet pipe from the tank below the valve seal. Thus, its cavity is drained and renders the float buoyant when the flapper of which it forms a part is lifted. It floats above the valve seal at all times when the valve is open, because it is buoyant as the consequence of the air which it retains. When the tank runs out of water, the valve reseals, and pressure of the stored water keeps the valve closed until it is physically lifted again to start a new cycle.
Thus, the length of the cycle is whatever time it takes to empty the tank, because the float part will remain buoyant until all of the water in the tank is discharged. If variability of discharge volume, and speed of discharge are of little interest, this is a satisfactory system, and certainly it is in very widespread usage. However, water usage has become so critical that in many areas the conventional system is not acceptable.
The problems to be solved by any replacement are (1) to be fitted into existing systems, (2) to discharge a reduced volume of water quickly, and (3) to discharge an accurate amount of water in a consistent period of time. It is an object of this invention to provide a flush valve which solves these problems, which can be adapted for various rates and flows of discharges, and which is simple and inexpensive.
There does exist a flush valve with the above objectives: Angelo J. Conti U.S. Pat. No. 4,189,795. This flush valve has an adjustable orifice into the bottom of its cavity, and a bleed port at its upper end which allows the air to bleed from the cavity when the float has been lifted. Then it gradually loses its buoyancy, and closes the flush valve, even while there still is water in the tank.
This invention uses the same basic scheme in order for the float to lose its buoyancy sooner, thereby to shorten the flush time and discharge. It is also intended to correct some deficiencies in the Conti valve.
The repetitiveness and timing of the flush are heavily dependent on the consistency of the float's buoyancy. For example, any water retained in the float while the valve is seated will change the buoyancy and the time it takes for the float to lose its buoyancy. The Conti patent valve has a latent volume that may not drain. Also it is quite complicated and is more expensive to make than it should be. Toilet valves are intensely competitive, and a few cents more of cost can lose sales.
A flush valve according to this invention drains quickly and consistently. Its orifice is readily exchanged for one of another size, and its operation is independent of the depth of water in the tank, another advantage.